Strong coupling of lattice and orbital excitations in the quantum magnet Ca10 Cr7 O28: Anomalous temperature dependence of Raman phonons

Pal, S and Seth, A and Ali, A and Singh, Y and Muthu, DVS and Bhattacharjee, S and Sood, AK (2023) Strong coupling of lattice and orbital excitations in the quantum magnet Ca10 Cr7 O28: Anomalous temperature dependence of Raman phonons. In: Physical Review B, 108 (24).

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Abstract

We report low-temperature Raman signatures of the Heisenberg quantum magnet Ca10Cr7O28, showing clear anomalies in phonon mode frequencies and linewidths below �100 K. This crossover temperature lies in between the Jahn-Teller (JT) temperature scale (>room temperature) and the temperature scale associated with the spin exchange interactions (<12 K). Our experimental observation is well captured by a secondary JT transition associated with a cooperative reorientation of the orbitals giving rise to anomalies in the temperature dependence of Raman frequencies and linewidths. Such orbital reorganization, in turn, affects the spin-spin exchange interactions that decide the fate of the magnet at lower temperatures and hence provide important clues to understand the energetics of the possible lower-temperature quantum paramagnetic phase. © 2023 American Physical Society.

Item Type:	Journal Article
Publication:	Physical Review B
Publisher:	American Physical Society
Additional Information:	The copyright for this article belongs to authors.
Keywords:	Exchange interactions; Phonons; Temperature distribution, Heisenberg quantum magnet; Lows-temperatures; Mode frequencies; Orbital excitations; Orbitals; Phonon mode; Quantum magnets; Raman signatures; Strong-coupling; Temperature dependence, Temperature scales
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	30 Oct 2024 11:16
Last Modified:	30 Oct 2024 11:16
URI:	http://eprints.iisc.ac.in/id/eprint/85305

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